got a skip under load

[parttime]

i have noticed a skip when i get on to it and its getting worse, i changed fuel filter and is still the same, it does fine when driving normal. the tranny shifts fine under normal and seems to act up when i get on it as well.this is on a 03. i had it studded,egr deleted, 8new injectors, IRP valve, ICP sensor, UVC harnesses and and a new hp oil pump back in dec 09 and the truck has only been driving 7k miles since then. i put it back to stock tune and it still does it. any thoughts

[LHMissions]

I'll assume your '03 is the 6.0?

Is it the engine skipping or the trans? How many miles are on it?

[parttime]

Truck has 128k and the tranny has around 15k. it is deffintely something with the engine and not the tranny. I am thinking maybe fuel pressure related but not sure. I am going to my 6.0 guy tomorrow and hopefully he will get it figured out, he is also thinking fuel pressure from what i am telling him by phone.he is going to bring the ford laptop and program home with him, if it is the fuel pump going then i will just go ahead and do a AirDog system.